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vacon • 6

BASIC TOPOLOGIES FOR CONNECTION

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BASIC TOPOLOGIES FOR CONNECTION

The basic connections are divided into multible possibilities.

Table 2. Basic connections

Use case

Topology

Pros

Cons

Common DC energy
storage connection

• No competitive

"technology" when
DC-grid connec-
tion needed

• Different storage

voltage/techno-
logy adaptations

Energy storage to AC-
grid with combination of
DC/DC con grid
converter

• Different storage

voltage/techno-
logy adaptations

• Expansion easy
• Battery stack

replacing due to
ageing

• Large number of

components

• Lack of efficiency
• Size

Energy storage directly to
AC-grid with grid
converter

• Small number of

components

• Efficiency
• Size
• Power vs. energy

dimensioning is
independent from
each other

• Expansion difficult
• Battery stack

replacing due to
ageing

Energy storage close to
load and AC-grid with
DC/DC converter con-
nected between DC-link
and storage

• Load power/

energy support
close the con-
sumption

• Different storage

voltage/techno-
logy adaptations

• Expansion easy
• Battery stack

replacing due to
ageing

• Large number of

components

• Size

Filter

Summary of Contents for NX6

Page 1: ...vacon nx ac drives design guide hybridization ...

Page 2: ......

Page 3: ...r 22 5 2 2 Control Structure 34 6 PRODUCT CONFIGURATION EXAMPLES 36 6 1 Scope of delivery 36 6 1 1 Direct to DC 36 6 1 2 DC to DC 37 6 2 Example configurations 39 6 2 1 DC DC for supply interruptions 39 6 2 2 Direct DC for Grid Support 40 7 SIZING OF THE SYSTEM AND PRODUCT 41 7 1 Direct to DC 41 7 2 DC DC 42 8 INFORMATION TO ACQUIRE FROM CUSTOMERS 47 NOTE You can download the English and French pr...

Page 4: ...of Common Point of Coupling Typical use cases are time shift for production peak load shaving for distribution smoothen load for average energy backup power or black out start grid support Figure 1 Power balancing Energy Production kW Average Power t Charging Discharging Process Power Grid Power kW Average Power t Charging Discharging ...

Page 5: ...rgy application Another relevant thing to note is the dynamic requirements of the application Determining the application Energy vs power kW kWh ratio Dynamic requirements o Grid support functions Harmonics FRT o Bulk energy time shift Figure 2 Power vs energy Time h Power Energy MW MWh 4 1 3 1 2 1 1 1 1 1 1 4 1 2 1 3 1 4 Time h Time h Power MW Power MW Power MW Power Applications Energy Applicati...

Page 6: ...tors D NiMH Battery type Energy density Wh kg Power density W kg Service life in cycles years Lead acid battery 30 50 150 300 300 1 000 3 5 Nickel metal hybride battery 60 80 200 300 1 000 5 Lithium ion battery 90 150 500 2 000 2 000 5 10 Spercaps double layer capac 3 5 2 000 10 000 1 000 000 unlimited B A C D E F G 100s 1 000s 1 000 100 10 1 0 1 0 01 10 100 1 000 10 000 10 000s 10s 1s 0 1s Energy...

Page 7: ...d current used with a 1A current would mean 0 1C or C1 In the same example 2C would mean 20A Reference Reference A Energy management Dicharge time B Bridging power C Power quality CAES Compressed air Ni Cd Nickel cadmium EDLC Dbl layer capacitors Ni MH Nickel metal hybride FW Flywheels PSH Pumped hydro L A Lead acid VR Vanadium redox Li ion Lithium ion Zn Br Zinc bromine Na S Sodium sulfur A C B 1...

Page 8: ...ltage techno logy adaptations Expansion easy Battery stack replacing due to ageing Large number of components Lack of efficiency Size Energy storage directly to AC grid with grid converter Small number of components Efficiency Size Power vs energy dimensioning is independent from each other Expansion difficult Battery stack replacing due to ageing Energy storage close to load and AC grid with DC D...

Page 9: ...rid with direct DC link connection Load power energy support close the consumption Large number of components Efficiency Size Power vs energy dimensioning is independent from each other Voltage window limiting the scope only in range of 400 Vac using DC range 600 1100 Vdc System expansion later with additional batteries difficult Filter ...

Page 10: ...arger or a maintenance charger is needed in some cases 3 1 Voltage window For both the DC DC converter and the GTC Grid Tie Converter the first dimensioning question comes from energy storage battery voltage dimensioning It is important to define the voltage window for empty and full battery cell voltage Depending on battery chemistry the ratio can be full empty 1 2 2 meaning for example full bein...

Page 11: ... in a controlled way from full to empty value or from empty to full value For example if the battery is wanted to be discharged in 30 s 300V voltage window from 1000 Vdc 700 Vdc it means roughly 10 V s voltage change of rate This is huge difference in comparison to for example case where discharge time is longer say 30 min resulting in 0 2 V s This way the SOC State of Charge behavior is observed ...

Page 12: ...isible in higher stretch of voltage levels needed in controlling the battery Figure 8 Number of batteries Figure 9 Battery sizing effect on voltage change during equal power changes The spring analogy works also when thinking of parallelizing of batteries springs The more you have batteries springs in parallel the less you need to use voltage stretch to gain the same response 1 2 3 4 5 6 1 2 3 4 5...

Page 13: ...e DC bus Udc 2 or to negative DC bus Udc 2 sum of output voltages is always unequal to zero The common mode voltage CM voltage Ucm can be calculated as average of output voltages Table 3 presents all possible common mode voltages produced by different switching states Used reference point is in the middle of the DC link Table 3 Common mode voltage as function of modulation sequence Switching vecto...

Page 14: ...quency but also higher frequencies will be present As an example a typical measured DC to ground voltage can be seen in Figure 11 A rule of thumb is that with a typical DC link voltage 1025V the voltage spikes will be about 1 5kV Curve info max min rms UDC 2 171 171 171 UDC 6 512 512 512 ___ CM voltage 512 512 264 600 400 40 40 10 40 20 40 30 40 40 40 50 Time ms 40 60 40 70 40 80 40 90 41 200 0 20...

Page 15: ...ow a transformer star point instead of a motor stator star point that shall not be grounded Figure 12 Transformer must be isolated from ground In the grid side filter if LCL is used the grounded capacitors cannot be kept connected to ground If transformer inductance is bigger or at least the same as proposed grid side inductance it is possible to use only an LC filter sine to avoid additional volt...

Page 16: ...y Management System can safely tune its SOC value back to 100 Every cell must be charged extremely slowly so that the current of each cell goes as low as possible the cell reaches its full voltage For a big battery system that has many cells in parallel and in serial this is done from the same DC and DC connections with the same Udc control Do not start to dismantle batteries to charge them indivi...

Page 17: ...ower Management System includes controlling of power balance in a system that has multiple energy power sources Normal time scales are from grid cycle 20ms 50Hz to seconds The Power Conversion System of this list is the system relevant to the product The PCS includes Power Conversion Control and Power Conversion Hardware which is the VACON hardware It is to control power conversion between the ene...

Page 18: ... 358 0 201 2121 Fax 358 0 201 212 285 Figure 15 Typical system layers Energy Management System EMS Power Management System PMS Power Conversion System Power Conversion Hardware Power Conversion Control PCC Battery Management System Battery Storage System ...

Page 19: ...onverter DC DC converter Connection to AC or DC Direct to DC Application Control ref P Udc Idc Customer primary reference Customer system tailoring Control modes Island AFE uGrid Voltage window AC small large Grid Converter needed in all cases Grid Converter needed in all cases DC Filter Filter Filter Filter Filter Filter Filter For example VACON Common DC buss ...

Page 20: ... Direct to DC connection D Note that the storage topology does not affect the allowed or not allowed topology of the connection to the system There might however be other limitations for example voltage or current ratings Figure 17 Options A B C D Table 4 OK Configuration Notes No grounding allowed in transformer No HF EMC capacitors in LCL OK OK transformerhas enough inductance to satisfy filteri...

Page 21: ...age pattern which creates circulating current Not OK if grid selectivity is needed speciallyfor uGrid Not OK if grid selectivity is needed speciallyfor uGrid 3 3 3 3 Options A B C D Options A B C D 3 3 3 3 Options A B C D Options A B C D 3 3 Options A B C D Options A B C D 3 3 3 3 Options A B C D Options A B C D Options A B C D Options A B C D 3 3 3 3 ...

Page 22: ... 280 513 708 Vdc DC low run Def estim 242 475 656 Vdc DC low ready Stop 239 436 602 Vdc DC low running min 225 410 567 Vdc Under voltage instantly 183 333 461 Vdc Reference Reference A Maximum tolerable UDC voltage for AFE operation B Minimum tolerable UDC voltage for AFE to stay in grid with cosᵩ 1 A B Filter Filter voltage drop Transformer voltage ratio and drop 0 20 40 60 80 100 1C 2C 3C 6C 9C ...

Page 23: ...n operating parallel with other power sources Reference is base current reference If the device is operating in island mode the power reference changes the frequency o Grid frequency variations will affect what will be actual power to the grid Operates like a normal generator Power reference is several times faster than a normal diesel generator Frequency drop in a grid will increase Grid Converte...

Page 24: ...rence o Cannot make or maintain grid by itself needs existing grid Island operation mode o Power control not possible drive will give to the grid what the grid needs o Cannot operate parallel with other power sources o Makes a grid but cannot synchronize to the existing one When doing maintenance charging with the aim of a 100 full battery charging must be done with DC reference possibly with a ch...

Page 25: ...re 22 Interleaved filter topology Reference Reference A Maximum full battery UBattery voltage for fixed AFE reference voltage operation B Minimum tolerable UBattery voltage for DC DC filter current ripple B A Filter Filter voltage drop 0 20 40 60 80 100 1C 2C 3C 6C 9C uINU uAFE AFE DC Grid converter INU AC AFE AC SOC Rectifying DC AC and AFE control marginal Battery DC L L L HF HF ...

Page 26: ...dual phase current ripple Thus while the sum current is multiplied by factor of three the maximum relative output current ripple is reduced to 1 9 The equivalent switching frequency in the output is three times the switching frequency Figure 24 Example simulation with interleaved control and d 1 2 leg currents and sum current I 100 A leg L 2050 uH Udc 1025V Curve info rms max min peak to peak I 1 ...

Page 27: ...or the filter choke can be calculated as follows It is important to note that the ripple depends on duty cycle which is defined as follows Curve info rms max min pk2pk I 1 100 2 112 6 87 4 25 2 I 2 100 2 112 6 87 4 25 2 I 3 100 2 112 6 87 4 25 2 I Battery 300 7 337 9 262 1 75 7 350 I A Time ms Currents Interleaved 300 250 200 150 100 50 40 40 10 40 20 40 30 40 40 40 50 40 60 40 70 40 80 40 90 41 I...

Page 28: ... is either low or high When 1 3 d 2 3 one switch is low one high and one is either low or high And when d 2 3 two switches are always high and one either low or high With d 1 3 and d 2 3 output ripple is in theory cancelled In practice simultaneous switching prohibit causes some ripple Disabling simultaneous switching prohibit logic will reduce fluctuation near d 2 3 and d 1 3 considerably The max...

Page 29: ...ed formula to calculate the required inductance is Using the above filter dimensioning the relative output ripple is Example with a 3 peak to peak The ripple current is a triangle wave and the RMS value is peak to peak divided by 2 i e 0 8 RMS A more general formula for inductance calculation is This can be used for example with powder core chokes which tolerate more ripple With liquid cooling pea...

Page 30: ...wer losses When the design is ready switching frequency decrease is not allowed otherwise ripple will increase and this can cause temperature problems In an LCL filter structure a smaller switching frequency can also cause resonances The inductance of a traditional laminated iron core choke usually remains constant LNOM up to saturation point INOM PEAK in Figure 28 below After saturation point the...

Page 31: ...n standard AC applications Because of tolerance switching frequency is not totally eliminated from the output current This will increase the ripple and can cause some resonance issues with optional filtering capacitors Tolerances also increase decrease individual peak to peak ripple currents of chokes Figure 29 and Figure 30 Temperature tolerances are not typically a concern with the above mention...

Page 32: ...current I 100 A leg L 2050 uH Udc 1025V Leg U has 20 less inductance Curve info rms max min peak to peak I 1 100 4 116 0 83 9 32 1 I 2 100 3 113 0 87 0 26 0 I 3 100 3 113 0 87 0 26 0 I Batteri 300 0 307 6 292 4 15 2 350 I A Time ms I1 I3 I2 I Battery Currents Interleaved 300 250 200 150 100 50 40 40 10 40 20 40 30 40 40 40 50 40 60 40 70 40 80 40 90 41 ...

Page 33: ...urrent I 100 A leg L 2050 uH Udc 1025V Leg U has 20 less and leg W 20 more inductance Curve info rms max min peak to peak I 1 100 4 116 0 84 0 32 0 I 2 100 3 113 0 87 0 25 9 I 3 100 2 110 9 89 1 21 8 I Battery 300 0 308 4 291 6 16 9 350 I A Time ms I1 I3 I2 I Battery Currents Interleaved 300 250 200 150 100 50 40 40 10 40 20 40 30 40 40 40 50 40 60 40 70 40 80 40 90 41 ...

Page 34: ...e winding in one layer Figure 31 Simple filter consist of three separate chokes The target is that the filtering could be done with chokes only That is a simple solution and one benefit of not having capacitors is that switching the battery supercapacitor is possible without any current spikes When IGBTs are disabled the connection requires only that the DC link is higher or equal If the output cu...

Page 35: ...e of the converter side choke is one third because of the parallel connection In addition there can be resonance can happen between L1 and C or L2 and C All these resonance frequencies must be well below the switching frequency In standard inverter applications the LCL circuit resonance frequency is usually one third of the switching frequency Because equivalent switching frequency at output is th...

Page 36: ...y In this case it is estimated that half of the switching frequency would be small enough with interleaving In addition the battery side choke L2 is determined as 1 6 of L1 which corresponds to the typical inductance ratio of chokes in standard inverter applications With these assumptions the required capacitance minimum value can be calculated as Without testing the interleaving capacitor must be...

Page 37: ...e is operating in island mode the power reference changes the frequency Grid frequency variations will affect what will be actual power to the grid o Operates like a normal generator o Power reference is several times faster than a normal diesel generator o Frequency drop in a grid will increase grid converter power output without power refer ence Useful in situations here PMS is not fast enough o...

Page 38: ...e level where the voltage remains until the DC DC converter discharging current limit is reached Figure 36 Charging and discharging AFE operation mode o Not practical Could be possible when DC DC operated with under voltage control with a drooping But DC reference changes makes steep power changes Island operation mode o Power control not possible drive will give to the grid what the grid needs o ...

Page 39: ...el 6 1 1 Direct to DC The scope of delivery of VACON includes the typical VACON offering from power modules to system drive or other suitable switchgear The simplest delivery includes power modules LCL filters NXP controls with an application and a license All the rest is handled by the system integrator NOTE The selection of available power modules can be seen in a separate chart Energy Managemen...

Page 40: ... VACON includes the typical VACON offering from power modules to system drive or other suitable switchgear The simplest delivery includes power modules NXP controls with an application and a license Deliveries of single phase chokes are not preferred to be handled by VACON as the dimensioning varies case by case Still delivery of chokes is negotiable All the rest is handled by the system integrato...

Page 41: ...ed customer projects the scope of delivery may be a switchgear including power modules chokes NXP controls with an application and a license but also breakers fuses DC pre charging components and other possible control circuit Figure 41 Scope of delivery NXP NXI HW Customer Danfoss Danfoss Filter Application SW License Single Phase Choke ...

Page 42: ...he grid voltage drops Essential motors can run and ride through the voltage drops without interruption Figure 42 Failure ride through with undervoltage control The DC DC converter can be used to support the grid by equalizing the power peaks and producing the power if the main grid voltage drops The DC DC converter is connected to the grid converter and power can run in both directions by charging...

Page 43: ... battery voltage window is set to be 750 1100Vdc Figure 44 Peak shaving of higher power and high energy AC grid INCOMING 3PH AC SUPPLY INCOMING 3PH AC SUPPLY 3 2 2 3 QA1 2000A 3P LSI 65kA MAIN BREAKER FC1 1 FC1 3 RF4 1030A LCL FILTER TB1 NXA10306 AFE UNIT FC2 OEVA SWITCH TB1 NXA10306 AFE UNIT RF4 1030A LCL FILTER FC1 1 FC1 3 FC1 1 FC1 3 FC1 1 FC1 3 QA1 2000A 3P LSI 65kA MAIN BREAKER 3 3 3 3 3 3 I ...

Page 44: ...ensioning of the unit size An easy rule of thumb is that output voltage of grid converter is The gain 1 56 is not accurate and depending for example on voltage drop in filters and grid state Theoretically the gain can vary from 1 41 to 1 89 However 1 56 is a good starting point Now if the customer has indicated the needed power P the corresponding current Iac for calculated voltage Uac can be calc...

Page 45: ... the power converter There are two parts which are thermally stressed in the DC DC application The DC link busbars DC and DC which are dimensioned according to I 1 of the DC DC converter The IGBT switches in the DC DC converter due to high switching frequency There is a software current limiter in the DC DC converter to ensure these constraints are not violated The combined effect of the constrain...

Page 46: ...in vary depending on voltage class and switching frequency of the DC DC converter These values are higher when the switching frequency is decreased to 4 kHz and higher also for the NX5 voltage class units In addition the 1min limit applies only to frame sizes FI9 FI14 NOTE The nominal current of the DC DC converter is not the same as the inverter current rating You may roughly calculate the DC DC ...

Page 47: ...90 108 NXI00806A0TOCSSA FI8 IP100 92 95 91 143 117 143 117 143 NXI01006A0TOCSSA FI8 IP100 117 119 122 167 133 180 146 180 NXI01256AOTOISF FI9 IP100 146 149 188 250 183 228 183 228 183 228 NXI01446AOTOISF FI9 IP100 168 172 216 288 210 263 210 263 210 263 NXI01706AOTOISF FI9 IP100 198 203 255 340 231 309 248 311 248 311 NXI02086AOTOISF FI9 IP100 245 251 312 416 231 309 248 325 264 345 NXI02616AOTOIS...

Page 48: ...3 6kHz A Iout 5kHz A Iout 3 6kHz A NXI09206AOTOISF FI13 IP100 1102 1130 1380 1840 1275 1683 1346 1683 1346 1683 NXI10306AOTOISF FI13 IP100 1234 1265 1545 2060 1275 1645 1414 1780 1448 1884 NXI11806AOTOISF FI13 IP100 1414 1449 1770 2360 1275 1645 1414 1780 1448 1884 NXI15006AOTOISF FI14 IP100 1797 1842 2250 3000 2196 2745 2196 2745 2196 2745 NXI19006AOTOISF FI14 IP100 2276 2333 2850 3800 2568 3477 ...

Page 49: ...rage Power Storage g voltage g range Storage g Power Profile Storage g Current Profile Vdc kW Adc max voltage 700 350 500 g nom voltage 375 300 800 g min voltage 150 81 540 DC link voltage 750 Vdc Class_5 g DC link power 343 0 kW p DC link current 457 Adc dc link Storage output current 800 Adc storage wer Energy storage system parameters 750 Vdc Class_5 34 43 0 0 kW DC DC Converter design paramete...

Page 50: ...formation to be acquired from customer system to continue the discussion of the offering 1 Single line diagram 2 Short description of usage case mission profile wanted behavior 3 Battery storage information Voltage window UBat min UBat nom UBat max Power or current requirement at those voltage points UBat min UBat nom UBat max Balance Maintenance charger 4 Grid information Grid code demands 5 Pref...

Page 51: ...Document ID DPD01887A Rev A Vacon Ltd Member of the Danfoss Group Runsorintie 7 65380 Vaasa Finland www danfoss com ...

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